TiO₂ mesoporous thin film architecture as a tool to control Au nanoparticles growth and sensing capabilities

Abstract

Pore size and ordering in mesoporous TiO2 thin films define the Au nanoparticle growth through and inside the pores.

Gold semicontinuous thin-film-coated mesoporous TiO2 for SERS substrates

“…S1) and a thickness of 60 ± 6 nm. These results are in agreement with previously reported data for similar systems [29,56,57].…”

“…Moreover, NPs remain in contact with the medium thanks to the porosity. Different architectures were proposed for the combination of these two materials: metal NPs inside the mesostructured oxide film [26][27][28][29], metal NPs placed between the oxide film and the substrate [28][29][30][31][32], and metallic NPs or films in the air-oxide film interface [33][34][35][36][37][38]. Alternatively, metallic particles covered with a mesoporous shell can be deposited onto substrates to prepare films for SERS sensing [39,40].…”

“…While these kinds of sensors present very attractive features such as high chemical and mechanical stability, each architecture displays different sensing capabilities. For example, high spatial homogeneity of the SERS signal can be obtained when NPs are synthesized inside the mesoporous oxide film [27][28][29], while the mesoporous oxide film can be used as an active part of the sensor giving selectivity to the detection [30][31][32]. Nevertheless, when the plasmonic material is placed inside the mesoporous oxide film or in the substrate-oxide interface, Raman enhancement of the sensor may be attenuated because the SERS signal relies on NPs surface availability, NPs proximity and diffusion of the analyte within the pores.…”

Multi-Layered Mesoporous TiO2 Thin Films: Photoelectrodes with Improved Activity and Stability

“…Five steps, namely (i) precursor selection and initial sol preparation, (ii) deposition, (iii) controlled aging, (iv) template removal and (v) wall crystallization, govern the final film properties as Soler-Illia et al pointed out [62]. Recently, the same authors contributed to state-of-the-art designs of plasmon-enhanced MTTFs with structural control of both the host and SPR-active NPs guests [64][65][66][67][68]. Their groups prepared well-ordered MTTFs derived either from mild oxidative at 350 • C air calcination [64][65][66] or extractive template removal [67,68] and employed an impregnation-reduction method to introduce noble metal NPs.…”

Fractionation of block copolymers for pore size control and reduced dispersity in mesoporous inorganic thin films

“…Structural control over a bicontinuous porous inorganic network on the 10 nm length scale is crucial for the functioning of many mesoporous thin film architectures, as demonstrated for mesoporous sensors, [1][2][3] ( photo)catalysis, 4,5 photovoltaics, including perovskite 6 and dye-sensitized solar cells, 7 optical coatings, 8 protective barriers 9 and separation and purification membranes. 10,11 Besides the mean pore size, the resulting pore dispersity is another important material property, as evidenced in examples related to electrochemistry, 2 sensing, 12,13 and controlled release. 14,15 This is best showcased in mass transport-limited scenarios governed by the Knudsen diffusion.…”